Collection electrode (collectrode) for geo-electrochemical sampling

ABSTRACT

This invention relates to a novel geo-electrochemical sampling electrode and process. More specifically, this invention pertains to a novel ion collection electrode, and process, which can be used in the remote sampling of ions contained in ground water. This invention consists of a geo-electrochemical sampling apparatus comprising a hollow electrically non-conductive casing; an opening in the casing for enabling ions to be transported from the exterior of the casing to the interior of the casing, a cathode positioned in the interior of the casing, and electrically connected to the exterior of the casing; and, ion exchange resin contained in the interior of the casing between the cathode and the opening.

FIELD OF THE INVENTION

This invention relates to a novel geo-electrochemical sampling electrodeand process. More specifically, this invention pertains to a novel ioncollection electrode, and process, which can be used in the remotesampling of ions contained in ground water, either naturally occurringor from anthropologic sources.

BACKGROUND OF THE INVENTION

The electrogeochemical exploration method, CHIM, developed over twentyyears ago in the former Soviet Union, is claimed to be a means ofcollecting ions emanating from ore deposits concealed by thick cover(Goldberg et al., 1990). Available treatises on CHIM (the term is anacronym derived from the Russian phrase "Chastichnoe IzvlechennyeMetallov", meaning partial extraction of metals) in the English languageare limited. Summaries may be found in Shmakin (1985), Bloomstein(1990), and Antropova et al., (1992). The method is based on the premisethat an applied electric field will drive ions in the soil intospecially designed collector electrodes. Ions accumulate in anelectrolyte within the electrode. The electrolyte, typically nitric acidof 2N to 4N concentration, also serves to conduct current from the powersource to the soil through a low-permeability membrane of syntheticparchment located at the base of the electrode.

The CHIM technique can best be described as an geoelectrogeochemicalsampling method. It uses a DC electrical current to move mobile cationsinto special fluid-filled cathodes placed spatially on the earth'ssurface. Cation-collector electrodes have been designed and developed bythe United States Geological Survey (USGS) to practise the CHIM method.They are relatively easy to use and clean, hold liquid well, and have atransparent body so that field crews can monitor for leaks or otherproblems. The cation collectors used for tests conducted at the KokomoMine, Russell Gulch, Colo., have an inside diameter of 1.625 inches(4.128 cm) and an operational capacity of 150 ml.

Electrical contact to the ground is made through a disk of artificialparchment (type 1470) manufactured by the James River Paper Co.,Parchment, Mich. The parchment disks are cut to fit the lower cap andare held in place by an O-ring seal. In the absence of seal leaks, theelectrode will lose about 5-10 ml of electrolyte through the parchmentin 24 hours. A 99.6% pure titanium rod, 5 mm in diameter and 20 cm long,is used as the inner working cathode. The electrolyte used as thecation-collecting medium is 4N reagent-grade nitric acid.

The electrical current, generally ranging from 0.1 to 0.5 A, isconducted through the electrode for time intervals of several hours toseveral days. At the end of this time, the electrolyte and innerelectrodes are collected and analyzed for elements of interest. Animportant aspect of the CHIM method is that it samples only ions mobilein an electric field as opposed to the total quantity of a particularelement in the soil near an electrode. Where the mobile ions are relatedto a geochemical halo developed in cover above a deposit, CHIM samplesmay provide better definition of the concealed deposit than standardgeochemical methods.

David B. Smith et al., in an article entitled "Preliminary Studies ofthe CHIM Electrogeochemical Method at the Kokomo Mine, Russell Gulch,Colo.", Journal of Geochemical Exploration, 46 (1993), page 257-278,disclose the results of preliminary tests conducted at the Kokomo Mine,using the CHIM electrogeochemical method.

Specifically, the U.S. Geological Survey started a study of the CHIMmethod by conducting tests over a precious- and base-metal-bearingquartz vein covered with 3 m of colluvial soil and weathered bedrocknear the Kokomo Mine, Colo. The tests show that the CHIM method givesbetter definition of the vein than conventional soil geochemistry basedon a total-dissolution technique. The CHIM technique gives reproduciblegeo-chemical anomaly patterns, but the absolute concentrations depend onlocal site variability as well as temporal variations. Weak partialdissolutions of soils at the Kokomo Mine by an enzyme leach, a diluteacetic acid leach, and a dilute hydrochloric acid leach show resultscomparable to those from the CHIM method. This supports the idea thatthe CHIM technique is essentially a weak in-situ partial extractioninvolving only ions able to move in a weak electric field.

The technique uses a DC electrical current introduced into the earth todraw mobile cations into specially designed cathodes. Ions collected inthis manner constitute a geochemical sample of mobile ions extractedfrom soil in the vicinity of the electrode. The technique may be thoughtof as an in-situ partial chemical extraction.

The overall equipment used in the studies at the Kokomo Mine isgenerally similar to the Russian CHIM equipment in electrical capacity,with the addition of a multichannel, recording, ampere-hour meter. TheUSGS system has a capacity of 31 channels, 15 kW, 1000 V, and 43 A. Theprincipal components of the system are (1) power source, (2) ampere-hourrecorder, (3) current control rheostats, (4) current distributioncables, and (5) cation-collector electrodes (FIG. 2). The power sourceis a 15 kW diesel motor generator providing AC power to Zonge GGT-25transmitter. DC power from the GGT=25 transmitter goes to individualanode and cathode ampere-hour sensor units where the power is split into31 channels. Each of the 62 individual channels may be monitored forcurrent, and the ampere-hours delivered to each channel are recorded.From the ampere-hour recorder, current goes to banks of rheostats thatcontrol current to each cation collector, and from the rheostat banks tomulticonductor distribution cables. Take outs on the distribution cablesthen deliver current to individual electrodes. For studies at the KokomoMine, only cation collectors were used. The positive current conductorwas directly connected to 3 or 4 graphite bars buried in the ground,salted, and watered. These were placed about 100 m from the cathodearray.

Many unsolved problems remain not only in the utilization of the CHIMmethod as an exploration tool, but also in the basic understanding ofthe electrochemical processes involved. The major issues and problemsinclude the following:

1. Anion collection. Pathfinder elements such as Au, As, and Sb may bepresent as anionic species in the near-surface environment (Stumm andMorgan, 1981; Mann, 1984; Webster, 1986). Russian literature translatedin Bloomstein (1990) mentions briefly the importance of collecting andanalyzing anions but does not give any data or case histories.

2. Ion mobility in the vadose zone. The mechanism of ion mobility in anelectric field in dilute solution is well understood. However, in thevadose zone, where most CHIM collection occurs, and in the presence ofclays and organic matter that absorb ions, the process of ion mobilityis not well understood. If relative mobilities in the unsaturated soilare significantly different than those observed in dilute solution,selective collection could require alteration of conventionalinterpretation of CHIM data.

3. Destabilization processes at the soil-electrode interface. Elementspresent as either positive or negative complexes present problems forthe CHIM technique. Such complexes are not stable over a wide range ofpH. At the electrode-soil interface, these complexes may be destabilizedand thus prevented from entering the low-pH electrolyte.

4. Problematical analytical methods. The nitric acid solution from aCHIM cation collector poses analytical problems because the samplecontains very low concentrations of some important pathfinder cationssuch as Au in a matrix containing high concentrations of major cationssuch as Ca, Mg, Na, Fe, etc. As part of our CHIM research, referencesamples of the nitric acid solution from the CHIM runs have beenprepared for interlaboratory comparisons.

5. CHIM vs. partial extractions. In the study at the Kokomo Mine,certain partial-dissolution techniques gave results at least as good asthe more time-consuming and expensive CHIM method. More comparisons needto be made for various types of mineral deposits in a variety ofgeologic settings to determine if results from the CHIM method can beduplicated with partial-dissolution techniques.

SUMMARY OF THE INVENTION

The invention is directed to a geo-electrochemical sampling apparatuscomprising: (a) a hollow electrically non-conductive casing; (b) anopening in the casing for enabling ions to be transported from theexterior of the casing to the interior of the casing; (c) an electrodepositioned in the interior of the casing, the electrode beingelectrically connected to the exterior of the casing and being of acharge attractive to the ions; and (d) an ion exchange resin containedin the interior of the casing between the electrode and the opening.

The electrode according to the invention can be a cathode and the ionscan be cations. In the apparatus, a non-ion containing water such asdistilled water or purified water can be contained in the interior ofthe casing. The apparatus can include means for applying a negativevoltage to the cathode. A semi-permeable membrane can be positionedbetween the opening in the casing and the ion exchange resin containedin the interior of the casing. The semi-permeable membrane can beparchment.

The cathode can be constructed of titanium or a disk of titanium. Thecasing can be constructed of two detachable components and can beconstructed of plastic. The apparatus can include an azimuth partitionwhich divides the ion exchange resin into two groups.

The casing can have the shape of a hollow cup, with a cap which can bedetachably secured to the open end of the cup, the opening can belocated in the base of the cup or cap, and the cathode can be a disklocated at the base of the cup or cap and can be electrically connectedto the exterior through an opening in the base of the cup or cap.

The casing can be in the form of a hollow cylinder. The casing can havean elongated cylindrical shape with walls, the cathode can be a metaltube fixed to a flat disk axially disposed in the interior of thecylindrical casing, the ion exchange resin can be held in the volumebetween the cylindrical casing and the flat disk, and at least oneopening for ion exchange can be located in the walls of the casing.

In another aspect, the casing can have an elongated hollow cylindricalshape, the cathode can be an elongated metal rod extending throughsubstantially the length of the casing, the ion exchange resin can beheld in the annular volume between the rod and the walls of the casing,and the one or more openings can be in the circumferential wall of thecasing.

The ion exchange resin can be separated into a first upper group, asecond middle group and a third bottom group and the casing can havethree sets of openings therein which correspond with the first, secondand third groups of ion exchange resin.

The metal rod can be held in place in the casing by electrically inertstoppers to provide an annular volume between the cylindrical casing andthe internally disposed elongated rod. A cap can be detachably securedto one end of the elongated cylindrical casing and a second cap can bedetachably secured to an opposite end of the elongated cylindricalcasing. The casing can be constructed of polyvinylchloride. The ionexchange resin can be contained in a package which can be installed orremoved from the apparatus as a unit.

The apparatus can include first and second openings in the casing and anazimuth partition in the casing which divides the ion exchange resin inthe casing into first and second groups so that the ions receivedthrough a first opening and exchanged with the ion exchange resin in thefirst group are separate from the ions received through a second openingand exchanged with the ion exchange resins in the second group.

The invention also pertains to a method of sampling and analyzing groundwater for ions which comprises: (a) applying a high negative voltage toa cathode proximate to the ground water thereby attracting metalliccations in the ground water to the cathode; (b) exchanging the metalliccations for hydrogen ions in a hydrogen ion charged ion exchange resinto thereby deposit the metallic cations on the resin and release thehydrogen ions to the cathode; and (c) analyzing the cation exchangedresin for metal concentration.

The ion exchange resin which holds the deposited metallic cations can beashed and the metallic cations can be analyzed. The ashed ion exchangeresin can be analyzed by inductively coupled plasma mass spectrometry.

The invention is also directed to a method of focusing an ion collectionelectrode which is used to attract ions in ground water which comprises:(a) deploying a central collection electrode on or near the surface ofground in which ground water is found, and applying a high positive ornegative voltage to the electrode proximate to the ground water toattract ions of opposite charge to the collection electrode; and (b)deploying at least one peripheral focusing electrode on or near thesurface of the ground adjacent to but spaced from the central collectionelectrode and applying approximately the same voltage as that applied tothe central collection electrode to thereby focus the ions attracted tothe central collection electrode.

A negative voltage can be applied to the collection electrode andmetallic cations in the ground water can be attracted to the collectionelectrode. At least four peripheral collectrodes can be spatiallydeployed around the periphery of the central collection electrode sothat the central collection electrode tends to attract metallic cationsin the ground water from beside and below the central collectionelectrode.

The invention is also directed to a method of focusing a downholecollection electrode to sample ions in ground water which comprises: (a)dividing an upper region of the collection electrode into a firstcompartment containing ion exchange resin; (b) dividing a mid-region ofthe collection electrode into a second middle compartment containing ionexchange resin; (c) dividing a bottom region of the collection electrodeinto a third bottom compartment containing ion exchange resin; (d)deploying the collection electrode in a drill hole below ground level;(e) applying a high potential to the collection electrode, whereby thefirst compartment of the collection electrode tends to attract ions ofan opposite charge from above and beside the upper region of thecollection electrode to the ion exchange resin contained in the firstcompartment; whereby the second compartment of the collection electrodetends to attract ions of opposite charge located laterally of thecollection electrode to the ion exchange resin contained in the secondmiddle compartment; and whereby the third bottom compartment of thecollection electrode tends to attract ions of opposite charge locatedbeside and below the lower region of the collection electrode to the ionexchange resin contained in the third bottom compartment of thecollection electrode.

A negative voltage can be applied to the collection electrode andmetallic cations in the ground water can be attracted to the first,second and third compartments of the collection electrode.

The invention also pertains to a method of determining metal ioncontamination in ground waters in the region of an industrialinstallation, which comprises deploying an array of collectionelectrodes with ion exchange resins in the region of the industrialinstallation, negatively charging the collection electrodes on aperiodic basis to attract metal cations in the ground water surroundingthe industrial installation, to the respective collection electrodes andion exchange resins, and sampling on a periodic basis the ion exchangeresins to determine the extent of metal ion contamination in the groundwater.

Involved in each sampling procedure will be a remote return electrodenecessary to complete the current path. The remote return electrode isthe opposite polarity (voltage) to the collecting electrode. The remoteelectrode should be constructed of suitable material such as stainlesssteel. The remote return electrode can be, as well, a collectrode filledwith ion exchange resins to sample the appropriately charged ions whichwill be attracted.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate specific embodiments of the invention butwhich should not be construed as limiting or restricting the field orscope of the invention in any way.

FIG. 1 illustrates a front elevation exploded view of a surfacecollectrode.

FIG. 2 illustrates a plan view of the surface collectrode.

FIG. 3 illustrates a section view taken along section line A--A of FIG.1.

FIG. 4 illustrates a section view taken along section line B--B of FIG.1.

FIG. 5 illustrates a plan view of the cathode of the surfacecollectrode.

FIG. 6 illustrates an elevation of the cathode of the surfacecollectrode.

FIG. 7 illustrates a plan view of a down-hole collectrode.

FIG. 8 illustrates a left elevation of the down-hole collectrode.

FIG. 9 illustrates a section view taken along section line A--A of FIG.7.

FIG. 10 illustrates a section view taken along section line B--B of FIG.7.

FIG. 11 illustrates a section view taken along section line C--C of FIG.7.

FIG. 12 illustrates a section view taken along section line B--B of FIG.1, but including an azimuth partition.

FIG. 13 illustrates a plan view of a surface collectrode and the mannerin which ions in the earth are circumferentially attracted to thecollectrode.

FIG. 14 illustrates an elevation view of the surface collectrode placedin the earth, and the manner in which ions in the earth arehemispherically attracted to the collectrode.

FIG. 15 illustrates a plan view of a surface collectrode and an array ofancillary focusing electrodes deployed around the periphery of thecollectrode, and the manner in which ions in the earth are attracted tothe collectrode and the dispersed focusing electrodes.

FIG. 16 illustrates an elevation view of a surface collectrode and apair of ancillary focusing electrodes deployed on each side of thecentral surface collectrode, and the manner in which ions in the earthare attracted to the collectrode and the respective focusing electrodes.

FIG. 17 illustrates an elevation section view of a downhole collectrode,and the manner in which ions in the earth are attracted to the upper,middle and lower compartments of the collectrode.

FIG. 18 illustrates an elevation view of an industrial complex withsurface collectrodes distributed around the industrial complex, and themanner in which ions in the earth are attracted to the collectrodes tothereby detect ionic contamination in the earth surrounding theindustrial complex.

FIG. 19 illustrates a plan view of an industrial complex withcollectrodes deployed around the periphery of the industrial complex.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

I have invented a novel collection electrode (collectrode) and methodsof using the collectrode. The apparatus and methods of this inventionhave the ability to focus the ionic beam (the collecting path) so thatone can determine sample depth from the surface collectrodes andazimuth, and elevation angle and distance from the downholecollectrodes. The focus is built into the downhole electrode butfocusing electrodes are needed to focus the surface electrodes. Thecompiled information allows one to more accurately determine thelocation from which the specific ions were collected. The ability tofocus the ionic beam path is extremely useful, allowing one to be veryselective. Ion exchange resins are used as the ion collectors. Thecollectrode can be filled with generally ion free water such asdistilled water or purified water to facilitate ion transfer.

Referring to the drawings, FIG. 1 illustrates a front elevation explodedview of a surface collectrode 2, which is one embodiment of theinvention. The collectrode 2 is constructed basically in the shape of ahollow cylinder, which is constructed in two parts, a hollow plasticbody 4, preferably made of 80 polyvinylchloride (PVC), and a hollowscrew cap 6, also constructed preferably of 80 polyvinylchloride. ThePVC body 4 has right hand male square threads 8 formed along theexternal part of its body which intersects with the interior of thescrew cap 6. The cap 4 has a cathode 12 protruding from its solid baseend. Corresponding right hand female square threads are formed in theinterior of the cap 6, to mate with the male threads of body 4. Thefemale threads are not visible in FIG. 1.

FIG. 2 illustrates a plan view of the surface collectrode 2. The plasticbody 4 has a circular cross-section, with a circular hole 10 formed inthe top central area thereof.

FIG. 3 illustrates an exploded section view taken along section lineA--A of FIG. 1. As seen in FIG. 3, the plastic body 4 has a cathode 12extending through the hole 10 formed in the top surface of the plasticbody 4. Right hand square cut male threads 8 are formed around thecircumference of a lower portion of plastic body 4. The cylindricalinterior cavity of the hollow plastic body 4 is filled with ion exchangeresin 14, preferably Ionac (trade-mark) C-267, available from SybronCompany. Either cation exchange resins or anion exchange resins can beused depending on the potential applied (negative or positive) and thetype of ions selected for collection (either cations or anions). Asemi-permeable membrane 16, which is in the shape of a disk, fits alongthe base of the plastic body 4, and holds the ion exchange resins 14 andgenerally ion free water such as distilled water or purified water inplace in the interior of cap 4. The semi-permeable membrane is a cutcircular disc of parchment 01651 #120 manufactured by James River PaperCo.

FIG. 3 also illustrates in section view the construction of the cap 6.Right hand female square threads 18 are formed in the interiorcylindrical walls of the cap 6 and mate with the right hand square malethreads 8 of the plastic body 4. The number of male threads 8 and thenumber of female threads 18 should correspond so that the cap 6 can bescrewed onto the plastic body 4 to the point where semipermeable diskmembrane 16 fits snugly at the interior base of cap 6, and abutscircular hole 20, which is formed in the bottom flat circular base ofcap 6. Ion exchange into and out of the ion exchange resin beads 14 isconducted through hole 20 and semi-permeable membrane 16.

FIG. 4 illustrates a section view taken along section line B--B ofFIG. 1. The plastic body 4 has a hollow circular configuration, incross-section, and contains the ion exchange resin 14. A tube 24, whichforms part of the central cathode, is located in the central axial areaof the plastic body 4.

FIG. 5 illustrates a plan view of the cathode 12, which is of a circularconfiguration comprising cathode disk 22 and cathode tubing 24.

FIG. 6 illustrates an elevation view of the cathode 12, and specificallythe cathode disk 22 and the cathode tubing 24. The disk 22 is preferablyformed of titanium plate. The tube 24 is also preferably formed oftitanium. The tube 24 is vertically affixed in a suitable manner such aswelding to the central area of one side of the disk 22. As seen in FIGS.1 and 3, the cathode tube 24 protrudes through the hole 10 formed in thetop of the plastic body 4.

FIG. 7 illustrates a plan view of a down-hole collectrode 30, which is asecond embodiment of the invention. This design of collectrode 30 issuitable for downhole sampling ground water in a hole drilled in theground. As shown in FIG. 7, the down-hole collectrode 30 has a long,cylindrical configuration comprising a cylindrical body 32, preferablyconstructed of Schedule 80 polyvinylchloride pipe, which has a first cap38 secured to one end thereof, and a second cap 48 secured to theopposite end thereof. A series of linear slots 34 are cut in parallelgroups along a major interior portion of the length of the cylindricalmain body 32, between end caps 38 and 48. An electrical cord 36 extendsfrom the free end of first cap 38.

FIG. 8 illustrates a left elevation of the down-hole collectrode 30.Specifically, FIG. 8 illustrates the cap 38, which has a circularcross-section and a central hole 54 through which electrical cord 36 ispassed.

FIG. 9 illustrates a section view taken along section line A--A of FIG.7. FIG. 9 illustrates in detail the construction of the hollowcylindrical main body 32, and the manner in which the male threads onfirst end cap 38 fits by female threads at one end of main body 32, andthe female threads of the second cap 48 fits by male threads at theother end of main body 32. These threads can be reversed, or both setscan be male or female. First cap 38 has a hollow, cylindricalconfiguration with a hole 54 formed in the flat base end thereof, whichaccommodates the electrical cord 36. At the other end, first cap 38 hasright hand male square threads 40 formed at the end opposite hole 54.These right hand male threads 40 fit within corresponding right handfemale threads 44 formed in the interior at first end of hollowcylindrical body 32. At the opposite end, the main body 32 has formed inthe exterior end surface thereof right hand male square threads 46,which correspond to and mate with right hand female square threads 50,which are formed in the interior of second cap 48.

Extending along most of the interior axial length of the down-holecollectrode 30 is an electrically conducting rod 52, which is preferablyformed of a metal such as titanium or stainless steel. The electricalcord 36, which enters the interior of first cap 38 through end hole 54,is connected to the adjacent end of the steel rod 52 by silver solder56. First cap 38 is then preferably filled with an electrically inertpotting compound to hold the cord 36 and the end of the steel rod 52 inplace in the interior of the cap 38 and body 32. Four spaced rubberstoppers 60 are installed throughout the axial interior of cylindricalmain body 32, which encloses the main portion of the cylindricalstainless steel rod 52. The rubber stoppers compartmentalize thedownhole electrode into three compartments, an upper compartment, amiddle compartment and a lower compartment. Three batches of ionexchange resin 62 are enclosed in the respective individual annularcompartments formed by the interior walls of the cylindrical main body32, the exterior surface of the long steel rod 52, and the stoppers 60.The electrical cord 36 is preferably flexible twelve gauge strand copperinsulated with a suitable electrical insulation. The main cylindricalbody 32, the first cap 38 and the second cap 48 are preferably formed of80 Polyvinylchloride pipe. The ion exchange resin is preferably Ionac™C-267 and is available from Sybron Company. As discussed in detaillater, the central portion of the downhole collectrode may also containone or more azimuth partitions (not shown). These partitions facilitatedetermining the direction (azimuth) that the ions originate from.

As can be seen in plan view in FIG. 7, the series of parallel linearslots 34 are arranged in three groups. These three groups correspondrespectively with the locations of the three compartments in theinterior of the cylindrical body 32 between the four stoppers 60 whichhold the ion exchange resin 62 in three groups. This open slot patternallows direct communication between the interior and exterior andpermits the external ions to pass through the slots into the ionexchange resins.

FIG. 10 illustrates a section view taken along section line B--B of FIG.7. In particular, FIG. 10 illustrates the circular cross-sectionalconfiguration of main cylindrical body 32, and centrally disposed rod52. The ion exchange resin 62 is confined in the interior annular volumeformed between outer cylindrical body 32 and internal rod 52.

FIG. 11 illustrates a section view taken along section line C--C of FIG.7. As with FIG. 10, the ion exchange resin 62 is held in place in theannular volume formed between outer cylindrical body 32 and central rod52. FIG. 11 is helpful for illustrating the manner in which the slots 34are formed in opposite walls of cylindrical body 32.

FIG. 12 illustrates a section view of a surface electrode taken alongsection line B--B of FIG. 1, but including an azimuth partition.Specifically, the collectrode illustrated in FIG. 12 is of the samegeneral construction as the collectrode illustrated in FIG. 4 anddiscussed previously. It has a hollow plastic body with a hollowcircular configuration in cross-section and contains an ion exchangeresin 14 and a central tube 24. However, the configuration illustratedin FIG. 12 includes an azimuthal partition plate 64, which isolates theion exchange resin 14 into two compartments, one on each side of thecollectrode. As indicated by the arrows 66 on the left side, and thearrows 68 on the right side, which represent ion travel paths, the ionson each side of the collectrode are attracted to the proximate ionexchange resins on respective sides of the partition 64. In this way, byanalyzing the resin on the respective side of the partition 64, it ispossible to determine which side of the collectrode the ions wereattracted from. While FIG. 12 illustrates a surface collectrode, it willbe understood that the azimuthal partition 64 can, for instance, beinstalled in the middle ion exchange resin compartment of thecollectrode illustrated in FIG. 9. The concepts of upper, middle andlower ion exchange resin compartments in the downhole collectrode arediscussed below in connection with FIG. 17.

Adapting the configuration illustrated in FIG. 12 to a downholecollectrode, considering only the middle compartment of the downholecollectrode, and an azimuthal partition in the middle compartment, onlythose ions flowing from the left, represented by arrows 66, will becollected by the ion exchange resin in the left hand portion of thecollectrode, while only those ions flowing from the right, representedby arrows 68, will be collected by the ion exchange resin on the rightside of the collectrode. This procedure will allow the collectrode userto determine which side (azimuth) has the greater concentration of theions of interest.

FIG. 13 illustrates a plan view of a surface collectrode and the mannerin which ions in the earth are circumferentially attracted to thecollectrode. Without the use of focusing electrodes, the ionsrepresented by arrows 70 are attracted to the surface collectrode 2according to a 360° pattern, as illustrated in FIG. 13.

FIG. 14 illustrates an elevation view of the surface collectrode placedin the earth, and the manner in which ions in the earth arehemispherically attracted to the collectrode. As seen in FIG. 14, thecollectrode 2 is partially immersed in the surface of the earth 71. Ascan be seen, the ions, represented by arrow 70, are attracted from allsides and below the collectrode 2, according to a hemispherical pattern.

FIG. 15 illustrates a plan view of a surface collectrode and an array ofancillary focusing electrodes deployed around the periphery of thecentral collectrode, and the manner in which ions in the earth areattracted to the collectrode and the deployed focusing electrodes. Asseen in FIG. 15, the surface collectrode 2 is centrally disposed, andattracts ions represented by arrows 72 from all sides. A number offocusing electrodes 74 are deployed around the periphery of thecollectrode 2. These focusing electrodes 74 individually attract ions asrepresented by arrows 76. In this way, the ions attracted to the centralcollectrode 2, represented by arrows 72, are more focused and localized.The focusing collectrodes 74 generally have the same potential as thecentral collectrode 2.

FIG. 16 illustrates an elevation view of a surface collectrode and apair of focusing electrodes deployed on each side of the collectrode,and the manner in which ions in the earth are attracted to thecollectrode and the respective focusing electrodes. FIG. 16 clearlyshows how the ions attracted to the central collectrode 2 are morefocused or localized from below the collectrode 2, as represented byupward arrows 72. This configuration, in effect, enables the user of thecentral collectrode 2 to focus on ions which are in the ground water inthe earth below the location of the central collectrode 2. The iontravel paths that are represented by arrows 76 below the focusingelectrodes 74, are attracted to the respective focusing electrodes 74and thus are not inclined to be attracted to the central collectrode 2.The electrode distribution pattern illustrated in FIGS. 15 and 16 can,of course, be varied to suit the individual focusing needs required todeal with the situation at hand. It will be understood that all sorts ofdifferent patterns can be used, while practising the fundamentalfocusing concepts of the invention.

FIG. 17 illustrates an elevation section view of the downholecollectrode, and the manner in which ions in the earth are attracted tothe upper, middle and lower compartments of the collectrode. As seen inFIG. 17, the fundamental design of the collectrode 2 is the same asillustrated and discussed previously in association with FIG. 9. As seenin FIG. 17, the ion exchange resins are separated into three separatecompartments, namely, an upper ion exchange resin compartment 80, amiddle ion exchange resin compartment 82, and a bottom ion exchangeresin compartment 84. This construction enables each compartment of thedownhole collectrode 2 to be focused, as indicated by the various ionicarrow patterns illustrated in FIG. 17. When the downhole collectrode isinstalled down a drill hole, the ions in the fluids in the downhole andthe surrounding earth, located to the side and above the collectrode 2,are attracted, as represented by ion arrows 86, to the upper ionexchange resin compartment 80. In similar fashion, but in invertedpattern, the ions in the drill hole fluids and the surrounding earthbelow and to the lower sides of the collectrode 2, as represented by ionarrow patterns 90, are attracted to the bottom ion exchange resincompartment 84.

Meanwhile, and of particular importance, those ions which are in thedrill hole fluids and the surrounding earth adjacent the middle ionexchange compartment 82 are attracted to the ion exchange resins in themiddle ion exchange resin compartment 82, as represented by ion arrows88. In this way, the middle compartment of the downhole collectrode 2can be focused laterally, since the middle ion exchange resincompartment 82 attracts only those ions which are moving laterally fromthe fluids, soil and rocks to the collectrode, and specifically, themiddle ion exchange resin compartment 82. Thus, by analyzing the ionexchange resins in the middle compartment 82, the collectrode user isable to determine the concentration of the ions that are distributedlaterally from the downhole collectrode 2.

This is an important aspect of the invention. By segmenting the downholeelectrode into three vertical sections, namely, an upper top compartment80, a middle compartment 82, and a bottom compartment 84, the downholecollectrode can be designed to sample ions from three directions, thosefrom above, those which move laterally from all sides of the downholecollectrode towards the middle ion exchange resin compartment 82, andthose from below the collectrode. In other words, the upper compartment80 will collect only those ions flowing down the fluids in the drillhole, and from above the collectrode 2. Similarly, the bottom ionexchange resin compartment 84 will sample only those ions flowing up thedrill hole in the fluids from below the collectrode. The middlecompartment 82 samples lateral ions.

If an azimuthal partition 64 is used, for instance, in the middle ionexchange resin compartment 82, then it is possible for the downholecollectrode to not only sample the ions flowing from lateral locationstowards the middle compartment of the collectrode, but it is alsopossible to determine from which side of the collectrode the respectiveions have originated. Thus it is possible to determine which side of thecollectrode has the higher ion concentration. Partitions can also beinstalled in one or both of the upper and bottom compartments.

FIG. 18 illustrates an elevation view of an industrial complex withcollectrodes distributed around the industrial complex, and the mannerin which ions in the earth are attracted to the collectrodes to therebydetect ionic contamination in the earth surrounding the industrialcomplex. FIG. 19 illustrates a plan view of the industrial complex withcollectrodes deployed around the periphery of the industrial complex.

As seen in FIG. 18, several shallow drill holes are located around anindustrial complex 92, and positive collectrodes 94 and negativecollectrodes 96 are deployed in the respective drill holes. If need be,one or more collectrodes can be deployed in the interior of theindustrial complex 92. These collectrodes can then be used to sampleions in the fluids in the earth surrounding the industrial complex 92,as represented by the directional arrows depicted in FIG. 18. FIG. 19illustrates the same industrial complex 92, with collectrodes 96positioned around the periphery of the industrial complex.

As a protocol, the collectrodes 94 and 96 can be energized over anextended period and the ion exchange resins which collect the ions inthe earth surrounding the industrial complex 92 can be sampled on amonthly basis. Any ionic contamination in the earth and earth fluidswill be attracted and collected by the respective collectrodes 94 and 96dispersed around and throughout the industrial complex 92. By analyzingthe ions collected in the ion exchange resins every month and plottingappropriate graphs, any contamination occurring in the earth eitherbelow or surrounding the industrial complex 92 can be tracked and, ifnecessary, curtailed by appropriate steps. The cost of operating such acollectrode pattern in an industrial complex would be minimal and sinceearly contamination of the earth in and around the complex 92 could bequickly detected on a monthly basis, expensive cleanups and problemswith the regulatory authorities can be avoided.

The collectrode of the invention can also be used from an environmentalstandpoint to detect leakage in various environments. The situationillustrated in FIGS. 18 and 19 represents only one application. Forinstance, the collectrode(s) according to the invention can be used tosample ground waters for environmental purposes such as ground watercontamination from tailings and residue ponds, mines, industrialoperations, dumps, stockpiles, and the like.

Application of Collectrode

The basic invention is a sampling electrode called a "Collectrode", anda method of using it. The device is intended for use ingeo-electrochemical sampling. The invention incorporates and is based onseveral geo-physical, geo-electrochemical, and electrochemicalprinciples.

The Russians, who have experimented with the same technique (CHIM), useconcentrated nitric acid in their collecting electrodes. Theseelectrodes are unattractive and undesirable because they leak acid,which dissolves minerals in and around the collecting site. Their systemrepresents an intrusive sampling device since it involves modifying thesoil around the sampled area. The use of acids is also dangerous and caninvolve environment risks.

The collectrode of the invention, on the other hand, is safe from allperspectives since it contains only distilled water and benign ionexchange resins, and is to be used in the remote sampling of ionscontained in ground water. The purpose of sampling of ions in the groundis that they can be extremely useful in the location of mineraldeposits, ground water pollution, or the levels of ions in ground water.The technique and collectrode of the invention can sample ions frommineral deposits which have been covered by transported materials suchas glacial till. The importance of being able to sample in areas coveredby transported soils is that normal soil geochemical exploration isineffective in these situations. The ions can either be free ionscontained in the ground water or ions loosely attached to clays above orwithin the ground water table. The source of the ions can be fromnatural sources such as those found around mineral deposits or they canbe from contamination sources.

A high negative voltage (200 to 2,000 VDC) is applied to the collectrodeand the positive charged ions (cations) in the soil and water are thenattracted to the negatively charged collectrode. The collectrodepreferably has a titanium plate which acts as the cathode. Thecollectrode is filled with ion exchange resins which are hydrogencharged, and distilled water. The surface collectrode has asemipermeable membrane on the bottom of the collectrode which is placeddirectly in the earth. Each positively charged ion in the soil passesinto the collectrode where it is exchanged with a hydrogen ion attachedto the ion exchange resin beads. The released hydrogen ion thencontinues on to the titanium cathode. The ion exchange resins have ahigher affinity for the metallic cations than they do for the hydrogen,thus all of the metallic cations drawn into the collectrode arecollected on the ion exchange resins. The collectrode is filled withdistilled water to facilitate transport of ions.

After the sampling is completed, a process which can take hours or days,the resins are then ashed and the ash analyzed using standard analyticaltechniques. The ion exchange resins and distilled water are very safe.The whole process represents a nonintrusive collecting device andsampling process. This sampling procedure can be used to sample ionsfrom deep sources covered by over 200 feet of material. In suchcircumstances, conventional soil sampling procedures are generallyineffective. The ionic makeup of the soil water reflects the makeup ofthe solid materials in the rock/soil. The sulphide mineralization oftengoes into solution and creates a large ionic halo around the sulphides.The interpreted results from the subject geo-electrochemical samplingusing the collectrode has identified sulphide mineral deposits whichotherwise would go undetected with conventional sampling methods. Thisprocedure is also useful in testing the ionic halo associated with somecontamination spills.

The collectrode which I have invented is considerably more sensitivethan the aforementioned Russian method (CHIM), or the device and methoddeveloped by the aforementioned United States Geological Survey. Asignificant advantage of the collectrode is that the electrical currentfrom the collectrode can be focused, which is not done in any otherprocedure. The focusing of the current is accomplished by locating 4 to8 focusing electrodes (stainless steel) around the collectrode at equalintervals. The focusing electrodes are usually placed from 3 meters to 5meters from the collectrode. The sensitivity and the ability of thecollectrode to focus the ion collection makes the method and collectrodeunique over prior devices and techniques. The downhole electrodes focusthe collecting currents by way of the three compartments, upper, middle,and lower, in conjuction with an azimuth portion.

The most appropriate use of the collectrode is geo-electrochemicalsampling in mineral exploration, and geo-electrochemical sampling ofenvironmental ionic contaminations. In either case, the uses are thesame, locating and identifying extremely low ion levels contained withinthe ground water, and associated clays in soil and rocks.

The normal ion variance is largely dependent upon the hydrologicalgradient. Typically, there should be a large dispersion of ions down thehydrological gradient from a large deposit. There should also bedispersion of ions along fractures which commonly conduct ground watermuch faster than unfractured rocks. Beyond this, the ionic variancesfrom closely spaced sample locations should not be great since the ionicdispersion is a smooth function, and the collectrode can effectivelysample a large volume. This volume will be larger for higher voltages,and longer durations. The effective sampling volume can vary from one totwo cubic meters up to several hundred cubic meters. The larger thevolume sampled, the smaller the variance in samples. Thus the varianceexpected is a function of time, and current levels or amp hours. It isnot possible to sample the same location twice and get the same readingssince the first sample would effectively sample that volume close to thecollectrode, and the second sample would effectively start samplingwhere the first left off.

Some ancillary material is carried into the collectrode on the ions andis not ionic. Some of this material can be organic. If it is necessaryto analyze the material, special handling procedures must be used. Thesampling of ions is what the collectrode has been designed for and theonly limitation is that one charge of ion exchange resins is good forabout 1 gram equivalent weights of ions, that is, approximately 50 gramsof various cations.

The principal advantages of the collectrode of the invention are:

(1) The collectrode uses ion exchange resins and distilled water ratherthan dangerous acids or other caustic chemicals.

(2) The ion exchange resins used in the collectrode capture all metallicions and are more sensitive than acids.

(3) The ion exchange resins are safe to handle, while acid electrodesrequire special precautions.

(4) The use of focusing electrodes has the ability to focus the current,and thus select the area to be sampled. This focusing featureconcentrates current downwards for the surface collectrode, verticallyand azimuthally for the down-hole collectrode. The sampling devices usedin the past are non focusing electrodes. The surface electrodes used byothers sample a hemisphere. The down-hole electrodes used by otherssample an entire sphere around the collecting electrode. The collectrodeof the invention is designed to employ the migration of ions (movementunder the force of a voltage potential) rather than by diffusion. Theapparatus and method of the invention rely strongly on the non-lineareffects of the high voltage upon the ions.

(5) The collectrode is non-intrusive and stable over a long duration ofsampling. Since the collectrode is a non-intrusive electrode, it doesnot react with the soil in which it is placed. The Russian system (CHIM)and possibly the U.S. Geological Survey system are intrusive systemsemploying nitric acid or other caustic chemicals to collect the ions.

(6) The metal cathode in the collectrode is composed of a flat titaniumdisk and a hollow titanium tube. This maximizes the surface area of thecathode which in turn maximizes the current flow. This design alsodistributes the collected ions throughout the ion exchange resin in thecollectrode. The collectrode and its method of use utilizes only highvoltage over long times. This maximizes the distance from which the ionscan be collected.

(7) The semipermeable membrane in the surface collectrode is held firmlybetween two plastic lips of the outer plastic shell which are screwedtogether. This forms a watertight seal and maximizes accuracy.

(8) The collectrode is constructed of plastic with a titanium disk, atitanium tube, and a parchment semipermeable membrane. All of thematerials used are nontoxic and no special handling procedures areneeded. The ion exchange resins are contained in a paper packet or nylonnetting which facilitates handling.

(9) After sampling has been completed, the ion exchange resins are ashedand then analyzed using inductively coupled plasma mass spectrometry(ICP). This is a different technique than using resins and thenextracting (back stripping) the ions using acids etc. The system of theinvention uses prepackaged cation exchange resins, which are placed as apacket into the holder. Voltage is then applied. At the end of aspecific sampling time, the packet is removed and the resins in thepacket are ashed at a high temperature such as 550 degrees F. The ash isthen analyzed using (ICP). The holder is filled with distilled waterduring the collecting time. The process of using distilled water andcation exchange resins in a packet then ashing and analyzing is uniqueand a significant improvement over the Russian acid based CHIM system.

(10) The apparatus and method of the invention have a definite use bothin base metal exploration and in the monitoring of low level ioniccontamination dispersions from contaminated sites.

The collectrodes can also function as anion collectors by exchanginganion exchange resins for the cation exchange resins and using a highpositive (+) potential rather than a high negative (-) potential. Thisis to be used when the ions being sampled are negatively charged ions.

The collectrode has been tested in various situations, some in thelaboratory and some in the field.

EXAMPLE 1

A group of the down-hole electrodes has been used experimentally at theMagmont mine in Missouri, U.S.A., to identify mineralization in closeproximity to a drill hole that had not intersected mineralization. Thedrilling itself did not indicate substantial mineralization in the hole.However, geo-electrochemical down-hole sampling using the collectrodeindicated substantial anomalies.

The system collected about 85% of the ions expected. This is incomparison to prior art acid systems which collect about 5% to 15%. Thetest was useful in determining the location of subeconomic and economicgrade mineral occurrences.

The area surveyed was thought to contain lead-zinc mineralization.Previously, a Geophysical Electromagnetic (EM) survey had traced themineralization from the working face of the mine to the south for some2500 feet. The mineralization is located in one bed which is nearlyflat. However, the mineralization is narrow, on the order of 30 to 40feet in width. The elevation of the terrain in the area is around 1300feet and the expected elevation of the mineralization was approximately300 feet, some 1000 feet below the surface.

Three drill holes were placed 100 feet apart MW-270, MW-271 and MW-272,to intersect the mineralization picked up in the EM survey. The drillholes were blank. This is not surprising since the EM could notaccurately locate a narrow layer of mineralization some 1000 feet belowthe surface.

The Magmont Mining Company was stymied since it had evidence there wasmineralization from the EM survey but could not intersect it withdrilling. The company decided to run a downhole Geo-Electrochemicalsurvey using the collectrode of the invention. The three holes weresurveyed.

The three downhole collectrodes were placed in the holes at the expectedelevation of the known mineralization. The collectrodes were energizedfor a period of three days, and at the end of that duration, wererecovered, and the resin was removed, ashed and analyzed.

The values are reported in PPM, ug, and ug/ah; the latter, ug/ah, areprobably the more useful values. In each case, drill hole MW-271 wasanomalous in zinc, lead and copper. This indicates that themineralization is close to MW-271. Since MW-270 values were low, it wasinterpreted that the mineralization was immediately to the east ofMW-271 and not between MW-270 and MW-271. MW-271 was also anomalous inseveral trace elements, such as molybdenum, cobalt and barium, all ofwhich are trace elements for the mineralization. However, such traceelements are not as important as lead, zinc and copper.

MW-272 was also moderately anomalous in lead, zinc and copper,indicating that there may be a smaller, less significant mineralizedzone nearby.

Three further holes, MW-275, MW-276 and MW-277 were also surveyed as theopportunity presented itself. MW-275 had trace mineralization present inthe hole. However, the two other holes were blank, even though they wereclose to known mineralized holes. The challenge was to determine ifanything significant was missed. MW-275 definitely had the best lead andzinc values, which is not surprising because it was in tracemineralization. The surprising feature was that the copper in MW-276 wasextremely anomalous. This is probably due to some high grade coppermineralization between drill holes MW-276 and USA-5.

MW-277 had low values for lead, zinc and copper even though it was closeto an ore grade intersection of MW-155. This was interpreted to indicatea rather abrupt termination of mineralization from MW-155 towardsMW-277.

The level of the ions as tabulated in the following Table 1, especiallyas reported in ug/ah, is exceptionally high. This is probably due to tworeasons. The area is mineralized, and the down-hole collectrode is anextremely efficient sampling instrument.

                                      TABLE 1                                     __________________________________________________________________________    VALUES REPORTED IN PPM                                                        __________________________________________________________________________    SVL #    28807 28808 28810 28812 28809 28811                                  CLIENT # 270   271   272   275   276   277                                    ALUMINUM 282   120   64.9  537   50    237                                    ANTIMONY <20   <20   <20   <20   <20   <20                                    ARSENIC  <20   <20   <20   <20   <20   <20                                    BARIUM   24.7  128   122   155   85.9  93.7                                   BERYLLIUM                                                                              <5    <5    <5    <5    <5    <5                                     BORON    42.4  9.57  3.32  36.8  8.06  15.0                                   CADMIUM  <2    <2    <2    <2    <2    <2                                     CALCIUM  51100 171000                                                                              186000                                                                              174000                                                                              159000                                                                              147000                                 CHROMIUM 28.0  9.77  19.9  45.2  14.6  28.1                                   COBALT   8.98  5.000 14.1  6.46  5.000 5.000                                  COPPER   15.9  89.3  326   115   1050  176                                    IRON     4040  2460  22900 8270  1510  2340                                   LEAD     61.6  43.8  39.5  662   116   39.7                                   MAGNESIUM                                                                              28500 59000 37300 28600 77800 71100                                  MANGANESE                                                                              61.2  21.2  590   118   12.8  74.0                                   MOLYBDENUM                                                                             5     5     5     8.61  5     5                                      NICKEL   25.9  10    76.2  108   13.4  28.9                                   PHOSPHORUS                                                                             50    50    50    68.9  50    50                                     POTASSIUM                                                                              1078  2270  4610  25900 2534  5150                                   SELENIUM 50    50    50    50    50    50                                     SILICON  248   176   91.9  388   142   436                                    SILVER   <5    <5    <5    <5    <5    <5                                     STRONTIUM                                                                              320   44.0  238   1010  140   231                                    SODIUM   46800 8720  5930  38100 7300  6350                                   THALLIUM <10   <10   <10   <10   <10   <10                                    VANADIUM <5    <5    <5    <5    <5    <5                                     ZINC     28.8  765   169   314   92.4  77.0                                   __________________________________________________________________________    VALUES REPORTED IN ug                                                         __________________________________________________________________________             270   271   272   275   276   277                                    grams    48.9  133.8 75.7  65.8  44.1  6.4                                    ALUMINUM 13789.8                                                                             16056 4912.93                                                                             35334.6                                                                             2205  1516.8                                 ANTIMONY 978   2676  1514  1316  882   128                                    ARSENIC  <978  <2676 <1514 <1316 <882  <128                                   BARIUM   1207.83                                                                             17126.4                                                                             9235.4                                                                              10199 3788.19                                                                             599.68                                 BERYLLIUM                                                                              <244.5                                                                              <669  <378.5                                                                              <329  <220.5                                                                              <32                                    BORON    2073.36                                                                             1280.47                                                                             251.324                                                                             2421.44                                                                             355.446                                                                             96                                     CADMIUM  <97.8 <267.6                                                                              <151.4                                                                              <131.6                                                                              <88.2 <12.8                                  CALCIUM  2498790                                                                             2.3E + 07                                                                           1.4E + 07                                                                           1.1E + 07                                                                           7011900                                                                             940800                                 CHROMIUM 1369.2                                                                              1307.23                                                                             1506.43                                                                             2974.16                                                                             643.86                                                                              179.84                                 COBALT   439.122                                                                             669   1067.37                                                                             425.068                                                                             220.5 32                                     COPPER   777.51                                                                              11948.3                                                                             24678.2                                                                             7567  46305 1126.4                                 IRON     197556                                                                              329148                                                                              1733530                                                                             544166                                                                              66591 14976                                  LEAD     3012.24                                                                             5860.44                                                                             2990.15                                                                             43559.6                                                                             5115.6                                                                              254.08                                 MAGNESIUM                                                                              1393650                                                                             7894200                                                                             2823610                                                                             1881880                                                                             3430980                                                                             455040                                 MANGANESE                                                                              2992.68                                                                             2836.56                                                                             44663 7764.4                                                                              564.48                                                                              473.6                                  MOLYBDENUM                                                                             244.5 669   378.5 566.538                                                                             220.5 32                                     NICKEL   1266.51                                                                             1338  5768.34                                                                             7106.4                                                                              590.94                                                                              184.96                                 PHOSPHORUS                                                                             2445  6690  3785  4533.62                                                                             2205  320                                    POTASSIUM                                                                              52714.2                                                                             303726                                                                              348977                                                                              1704220                                                                             111749                                                                              32960                                  SELENIUM 2445  6690  3785  3290  2205  320                                    SILICON  12127.2                                                                             23548.8                                                                             6956.83                                                                             25530.4                                                                             6262.2                                                                              2790.4                                 SILVER   <244.5                                                                              <669  <378.5                                                                              <329  <220.5                                                                              <32                                    STRONTIUM                                                                              15648 5887.2                                                                              18016.6                                                                             66458 6174  1478.4                                 SODIUM   2288520                                                                             1166736                                                                             448901                                                                              2506980                                                                             321930                                                                              40640                                  THALLIUM <489  <1338 <757  <658  <441  <64                                    VANADIUM <244.5                                                                              <669  <378.5                                                                              <329  <220.5                                                                              <32                                    ZINC     1408.32                                                                             102357                                                                              12793.3                                                                             20661.2                                                                             4074.84                                                                             492.8                                  __________________________________________________________________________    ALL VALUES REPORTED IN ug/ah                                                  __________________________________________________________________________    DRILL HOLE                                                                             270   271   272   275   276   277                                    ah       17.28 9.15  24.34 49    10.865                                                                              15.612                                 ALUMINUM 798   1755  202   721   203   97                                     ANTIMONY <57   <292  <62   <27   <81   <8                                     ARSENIC  57    292   62    27    81    8                                      BARIUM   70    1872  379   208   349   38                                     BERYLLIUM                                                                              <14   <73   <16   <7    <20   <2                                     BORON    120   140   10    49    33    6                                      CADMIUM  <6    <29   <6    <3    <8    <1                                     CALCIUM  144606                                                                              2500525                                                                             578480                                                                              233657                                                                              645366                                                                              60261                                  CHROMIUM 79    143   62    61    59    12                                     COBALT   25    73    44    9     20    2                                      COPPER   45    1306  1014  154   4262  72                                     IRON     11433 35972 71221 11105 6129  959                                    LEAD     174   640   123   889   471   16                                     MAGNESIUM                                                                              80651 862754                                                                              116007                                                                              38406 315783                                                                              29147                                  MANGANESE                                                                              173   310   1835  158   52    30                                     MOLYBDENUM                                                                             14    73    16    12    20    2                                      NICKEL   73    146   237   145   54    12                                     PHOSPHORUS                                                                             141   731   156   93    203   20                                     POTASSIUM                                                                              3051  33194 14338 34780 10285 2111                                   SELENIUM 141   731   156   67    203   20                                     SILICON  702   2574  286   521   576   179                                    SILVER   <14   <73   <16   <7    <20   <2                                     STRONTIUM                                                                              906   643   740   1356  568   95                                     SODIUM   132438                                                                              127512                                                                              18443 51163 29630 2603                                   THALLIUM <28   <146  <31   <13   <41   <4                                     VANADIUM <14   <73   <16   <7    <20   <2                                     ZINC     82    11187 526   422   375   32                                     __________________________________________________________________________

EXAMPLE 2

A group of the surface electrodes have been used experimentally inmineral exploration on the Pebble Copper Porphyry prospect in Alaska,U.S.A. The surface area is covered by glacially derived gravels. Soilgeochemistry did not give results that were diagnostic of buriedmineralization. In comparison, the surface geo-electrochemistry resultsfrom the surface electrode gave excellent indications of a buried copperdeposit.

There the collectrode was useful in extracting copper, molybdenum, zinc,lead and various other ions from the rock forming minerals such assodium and potassium from over 200 feet of glacial cover. This was in anarea where normal soil geochemistry did not function.

The Pebble Copper Project area was surveyed by two lines using thecollectrodes and geo-electrochemical sampling procedures according tothe invention. The survey was selected as a test because it had beenmapped, it had prior geophysics run on it and it had been drilled. Thisarea is also covered by glacial debris and normal soil samples do notreflect the presence of copper at depth.

The purpose of the test was to determine if anomalous values of copperwould be indicated using the Geo-electrochemical sampling procedures ofthe invention in areas of known mineralization covered by up to 250 feetof glacially derived material, where no appreciable soil sample anomalywas present when normal geochemical soil sampling procedures wereemployed. This was considered to be an ideal test since normal soilsampling procedures gave little indication of the amount of copper atdepth. The reason for this is that the soil was derived from transportedmaterial (by glacier) and the soil does not reflect the copper depositcovered by some 250 feet of this transported material. The area had alsobeen surveyed with induced polarization and resistivity. This allowedthe correlation of the Geo-electrochemical results with that of thedrilling, soil sampling, geology, and induced polarization surveys. Thetest Line 570+00 was also over a mineralized portion of the project.Line 388+00 was over lower values of copper.

The Geo-electrochemical test was run using normal field operatingprocedures. The collectrodes were placed along Line 570+00 N at 200 footintervals over a length of some 2000 feet. The tests were run over athree day period. The cation exchange resins in the collectrodes werethen collected, ashed, weighed, and analyzed using ICP. The results fromthe ICP were reported in ppm (parts per million) and percent. The valueof the analyzed material was multiplied by the weight of the ash givingvalues in μg (micrograms). This value was then divided by the product ofcurrent multiplied by time (amp hours or ah), to give μg/ah. This valueis useful when comparing values from one area to the next.

Another perhaps more meaningful method is to divide that value by thegram molecular weights of each element involved resulting in theμgmw/ah. This is a more important term when doing Geo-electrochemicaltesting. This allows the comparison of values from area to area, anddifferent elements, one to each other. This term is also referred to byCominco (an international mining company) as a Geo-electrochemicalSampling Unit (GSU). This is reported in μgmw/ah, (microgram molecularweights)/(amp hours).

Since, however, most other experimenters report data in ppm, or μg/ah,we have reported using those systems, so that a meaningful comparisoncan be made with reported data from other systems.

The data from the soil sample for copper are shown in Table 2. Thegeostatistical analysis of all of the copper in the soils indicates thatvalues of over 125 ppm Cu can be considered anomalous >80 percentile.Thus the line is lower than that threshold level. The values are notanomalous, and are not representative of the copper in the rocks becauseof the fact that the soil is transported from a remote site by glacialactivity.

Table 2 also contains the results from the Geo-electrochemical samplingprogram for the same locations as the soil samples. The values are shownas ppm for copper for the Geo-electrochemical sampling program and areextremely high.

                  TABLE 2                                                         ______________________________________                                               Ashed Resin                                                                   Geo-electrochemistry                                                                           Soil                                                  Station  ppm Cu       (μg/ah) Cu                                                                           ppm Cu                                        ______________________________________                                        57400    4900         42380     45                                            59900    4000         95420     35                                            60158    19900        96290     23                                            60300    7300         654670    30                                            60500    7600         265140    25                                            60700    16000        244140    19                                            60900    36800        258320    19                                            ______________________________________                                    

The above is only part of the line sampled. The average for the entireline was 229346 μg/ah with the highest value at 654670 μg/ah. The U.S.Geological Surveys reports that results of 1200 μg/ah are extremelyanomalous, being the highest that they had collected. Thus these valuesof 22934 μg/ah definitely are anomalous, indicating both a high level ofCu ions in the ground water, and an extremely efficient ion collectingelectrode. The line was not extended far enough east or west to obtainbackground readings. Other testing and logic dictates that values shouldgradually decrease away from the copper bearing zone reaching backgroundlevels of 4 to 5 ppm or 40 to 50 μg/ah. However, hydrodynamic dispersionfrom a large source such as a porphyry will create a large dispersionhalo.

The copper values can be compared to other rock forming minerals such ascalcium, iron, magnesium and potassium, as well as for those lessermetals such as lead, zinc, manganese, if the values are reported inμgmw/ah.

Table 3 gives the result for the value of other selected elements online 570+00 and 388+00 reported in μg/ah, and the expected relationshipas determined from normal porphyry zonal patterns.

                  TABLE 3                                                         ______________________________________                                                  Line     Line                                                                 570 + 00 388 + 00                                                   Element   μg/ah μg/ah   Expected Relationship                           ______________________________________                                        Cu        229364   144941     570 + 00 > 388 + 00                             Zn        24547    38934      570 + 00 < 388 + 00                             K         624515   154097     570 + 00 > 388 + 00                             Pb        7517     4310       570 + 00 < 388 + 00                             Si        177619   103420     570 + 00 > 388 + 00                             Fe        70912    60771      570 + 00 > 388 + 00                             Mo        103.6    90.2       570 + 00 > 388 + 00                             ______________________________________                                    

The copper values for line 388+00 are less than 570+00 N by a factor of2. This is the correct relationship since there was less copper there.There seems to be hydrodynamic dispersion of copper in that direction.

Table 3 is a listing of other selected elements that were sampled. Theresults reported are the average for that line. The interesting featurein these data is that the elements reflect the basic composition of thehost rock and alteration of the host rock. Porphyry copper deposits havea large potassium enriched core near the mineralization. The averagevalue for potassium for line 570+00 N is 624515 μg/ah and line 388+00 Nis 154097 μg/ah. This indicates that the ions sampled for line 570+00 Nwere derived from rock which contained much more potassium than line388+00 N. Line 570+00 N is generally inside the main mineralization andline 388+00 N is outside the main mineralization. The potassium valuesfrom the geo-electrochemistry sampling indicate the correct relationshipof the potassium values of the rocks from which the ions were derived.The other elements listed indicated the correct zonal alterationpatterns that one would see by doing whole rock geochemistry, with theexception of lead (Pb). Thus the ions sampled using the collectrode andthe geo-electrochemical sampling procedures of the invention seem toreflect the make-up of the whole rock. Thus it is possible that thegeo-electrochemistry of the invention has been sensitive enough toindicate whole rock geochemistry.

As will be apparent to those skilled in the art in the light of theforegoing disclosure, many alterations and modifications are possible inthe practice of this invention without departing from the spirit orscope thereof. Accordingly, the scope of the invention is to beconstrued in accordance with the substance defined by the followingclaims.

What is claimed is:
 1. A geo-electrochemical ground or ground water ionsampling apparatus comprising:(a) a hollow electrically non-conductivecasing; (b) an opening in the casing for enabling ions to be transportedfrom the exterior of the casing to the interior of the casing; (c) anelectrode positioned in the interior of the casing remote from theopening, said electrode being electrically connected to the exterior ofthe casing and being of a charge attractive to said ions; (d) ionexchange resin having ions of the same electrical charge as the groundor ground water ions contained in the interior of the casing between theelectrode and said opening; and (e) substantially ion free watercontained in the interior of the casing and surrounding the ion exchangeresin.
 2. An apparatus as claimed in claim 1 wherein the electrode is acathode having a negative potential of 200 to 2,000 volts DC and theions are cations.
 3. An apparatus as claimed in claim 2 including meansfor applying a negative voltage to the cathode.
 4. An apparatus asclaimed in claim 2 wherein a semipermeable membrane is positionedbetween the opening in the casing and the ion exchange resin containedin the interior of the casing.
 5. An apparatus as claimed in claim 4wherein the semipermeable membrane is parchment.
 6. An apparatus asclaimed in claim 4 wherein the casing is in the form of a hollowcylinder.
 7. An apparatus as claimed in claim 2 wherein the cathode isconstructed of titanium.
 8. An apparatus as claimed in claim 7 whereinthe cathode is a disk of titanium.
 9. An apparatus as claimed in claim 2including an azimuth partition which divides the ion exchange resin intotwo groups.
 10. An apparatus as claimed in claim 2 wherein the casinghas the shape of a hollow open-end cup, with a cap which can bedetachably secured to an open end of the cup, the opening being locatedat one end of the cap, and the cathode is a disk located at the base ofthe cup, and said disk is electrically connected to the exterior throughan aperture in the base of the cup.
 11. An apparatus as claimed in claim2 wherein the casing has a hollow cylindrical shape with walls, thecathode is a metal tube fixed to a flat disk axially disposed in theinterior of the cylindrical casing, the ion exchange resin is held in avolume between the cylindrical casing and the flat disk, and saidopening for ion transport is located in the end of the casing oppositethe disk.
 12. An apparatus as claimed in claim 2 wherein the casing hasan elongated hollow cylindrical shape, the cathode is an elongated metalrod extending through substantially the length of the casing, the ionexchange resin is held in an annular volume between the rod and thewalls of the casing, and the opening is in a circumferential wall of thecasing.
 13. An apparatus as claimed in claim 12 wherein the metal rod isheld in place by electrically inert stoppers to provide an annularvolume between the cylindrical casing and the internally disposed rod.14. An apparatus as claimed in claim 12 wherein the ion exchange resinis separated into a first upper group, a second middle group and a thirdbottom group and the casing has three sets of openings therein whichcorrespond with the first, second and third groups of ion exchangeresin.
 15. An apparatus as claimed in claim 12 wherein a cap isdetachably secured to one end of the elongated cylindrical casing. 16.An apparatus as claimed in claim 15 wherein a second cap is detachablysecured to an opposite end of the elongated cylindrical casing.
 17. Anapparatus as claimed in claim 16 wherein the casing is constructed ofpolyvinylchloride.
 18. An apparatus as claimed in claim 12 includingfirst and second openings in the casing and an azimuth partition in thecasing which divides the ion exchange resin in first and second groupsso that the ions received through the first opening and exchanged withthe ion exchange resin in the first group are separate from the ionsreceived through the second opening and exchanged with the ion exchangeresins in the second group.
 19. An apparatus as claimed in claim 1wherein the casing is constructed of two detachable components.
 20. Anapparatus as claimed in claim 1 wherein the casing is constructed ofplastic.
 21. An apparatus as claimed in claim 1 wherein the ion exchangeresin is contained in a package which can be installed or removed fromthe apparatus as a unit.
 22. A geo-electrochemical sampling apparatuscomprising:(a) a hollow electrically non-conductive casing; (b) anopening in the casing for enabling cations to be transported from theexterior of the casing to the interior of the casing; (c) a cathodepositioned in the interior of the casing, said cathode beingelectrically connected to the exterior of the casing; (d) ion exchangeresin contained in the interior of the casing between the cathode andthe opening; (e) a semi-permeable membrane positioned between theopening in the casing and the ion exchange resin contained in theinterior of the casing; and (f) generally ion free water contained inthe interior of the casing.
 23. An apparatus as claimed in claim 22including means for applying a negative voltage to the cathode.
 24. Anapparatus as claimed in claim 22 including an azimuth partition whichdivides the ion exchange resin into two groups.
 25. An apparatus asclaimed in claim 22 wherein the casing has the shape of a hollowopen-end cup, with a cap which can be detachably secured to an open-endof the cup, the opening being located at one end of the cap, and thecathode is a disk located at the base of the cup and said disk iselectrically connected to the exterior through an aperture in the baseof the cup.
 26. An apparatus as claimed in claim 22 wherein the casinghas an elongated hollow cylindrical shape, the cathode is an elongatedmetal rod extending through substantially the length of the casing, theion exchange resin is held in the annular volume between the rod and thewalls of the casing, and the opening is in the circumferential wall ofthe casing.
 27. An apparatus as claimed in claim 26 wherein the ionexchange resin is separated into a first upper group, a second middlegroup and a third bottom group and the casing has three sets of openingstherein which correspond with the first, second and third groups of ionexchange resin.
 28. An apparatus as claimed in claim 26 including firstand second openings in the casing and an azimuth partition in the casingwhich divides the ion exchange resin in first and second groups so thatthe ions received through the first opening and exchanged with the ionexchange resin in the first group are separate from the ions receivedthrough the second opening and exchanged with the ion exchange resins inthe second group.
 29. A geo-electrochemical ground or ground water ionsampling apparatus comprising:(a) a hollow electrically non-conductivecasing; (b) an opening in the casing for enabling ions in ground orground water exterior of the casing to be transported from the exteriorof the casing to the interior of the casing; (c) an electrode positionedin the interior of the casing remote from the opening, said electrodebeing electrically connected to the exterior of the casing and being ofa charge attractive to said ground or ground water ions; (d) an ionexchange resin contained in the interior of the casing between theelectrode and said opening, said ion exchange resin exchanging ionstransported from the ground or ground water for corresponding ions inthe ion exchange resin; and (e) generally ion free water contained inthe interior of the casing.
 30. An apparatus as claimed in claim 29wherein the ground or ground water ions transported to the interior ofthe casing are cations, the electrode has a negative charge, and the ionexchange resin is a hydrogen ion charged ion exchange resin.
 31. Anapparatus as claimed in claim 29 wherein the generally ion free water isdistilled or purified water.
 32. An apparatus as claimed in claim 29wherein the electrode has a negative potential of 200 to 2,000 volts DC.